| Effects of different mulching measures on soil N2O flux in rainfed winter wheat fields in the Loess Plateau of China |
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| DOI：10.7606/j.issn.1000-7601.2016.03.18 |
| Key Words: winter water dryland farming mulching N2O flux soil temperature soil moisture |
| Author Name | Affiliation | | LIU Quan-quan | College of Urban and Environmental Sciences, Northwest University, Xi'an, Shaanxi 710127, China | | WANG Jun | College of Urban and Environmental Sciences, Northwest University, Xi'an, Shaanxi 710127, China | | FU Xin | College of Urban and Environmental Sciences, Northwest University, Xi'an, Shaanxi 710127, China | | LIU Wen-zhao | Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi 712100, China | | Upendra M. Sainju | USDA-ARS Northern Plains Agricultural Research Laboratory, Sidney, MT 59270, USA |
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| Abstract: |
| Soil N2O flux and its responses to soil moisture and soil temperature under different mulching measures during the period of winter wheat growth were investigated at Changwu Agro-Ecological Research Station in the Loess Plateau of Changwu County, Shaanxi Province, China. The soil N2O flux rate, soil moisture and soil temperature were determined by the static chamber technique in the winter wheat field, with four mulching practices, including the control without mulching (CK), plastic film mulching (PM), two rates of 4 500 kg·hm-2 and 9 000 kg·hm-2 with straw mulching (M4500 and M9000) year-round. The results showed that the range of N2O flux during growth period for CK, PM, M4500 and M9000 were 17.24～321.86, 19.03～388.00, 21.57～344.53 μg·m-2·h-1 and 24.77～348.42 μg·m-2·h-1, respectively. The average N2O flux rates were 110.64, 146.48, 131.31 μg·m-2·h-1 and 142.26 μg·m-2·h-1 for the CK, PM, M4500 and M9000 treatments during the growth period, respectively. Compared to the CK treatment, the average N2O flux rates were increased by 32.39% for PM, 18.68% for M4500 and 28.57% for M9000. The cumulative N2O emissions for PM (7.25 kg·hm-2), M4500 (6.30 kg·hm-2) and M9000 (7.17 kg·hm-2) treatments were increased by 40%, 23% and 38% compared to CK (5.18 kg·hm-2), respectively, and PM and M9000 treatments significantly (P<0.05) increased the cumulative N2O emissions compared to M4500. No significant difference was found between PM and M9000. The obvious seasonal variation characteristics in the N2O flux were observed under all mulching measures, and the N2O flux was relative higher at the beginning and the end of the winter wheat growth peroid than that in the middle of the growth period. The cumulative N2O emission from jointing stage to harvest accounted for 41%, 40% and 43% of the total emission for PM, M4500 and M9000 treatments, which were higher than that in CK. Soil temperature itself could explain more than 69%～76% (R2＞0.43) variations in soil N2O flux, and soil water content only explained 37%～51% variations in soil N2O flux. The regression models including both soil temperature and soil moisture demonstrate that soil moisture is the dominant factor affecting soil N2O flux under the control without mulching, and soil temperature was the dominant factor affecting soil N2O flux under plastic film mulching and straw mulching. Straw mulching at a rate of 4 500 kg·hm-2 might be an appropriate way in the Loess Plateau. |
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